Sunan an-Nasa'i, Volume 5, Book 37, Hadith 4089 (DarusSalam) ⓘ
It was narrated that 'Abdullah bin 'Amr said: "I heard the Messenger of Allah [SAW] say: 'Whoever fights to protect his wealth and is killed, he is a martyr.'"
أَخْبَرَنَا مُحَمَّدُ بْنُ عَبْدِ الأَعْلَى، قَالَ حَدَّثَنَا خَالِدٌ، قَالَ حَدَّثَنَا حَاتِمٌ، عَنْ عَمْرِو بْنِ دِينَارٍ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، قَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ " مَنْ قَاتَلَ دُونَ مَالِهِ فَقُتِلَ فَهُوَ شَهِيدٌ " .
also referenced under: Hadith 4084 (Reference) & Book 37, Hadith 119 (In-Book)